1. Field of the Invention
The invention relates to a method and a device for detecting a specific material in an object, especially in a piece of luggage, using electromagnetic beams, whereby the intensities of non-absorbed beams from at least three beam planes in corresponding detector arrays are measured and evaluated.
2. Description of the Background Art
In conventional methods and devices for the inspection of objects, e.g., security screening of luggage at airports, the object is transported through electromagnetic rays, which radiate from stationary radiation sources. The intensities of the non-absorbed beams are measured and evaluated by the corresponding detector arrays assigned to the radiation sources. Generally, x-rays are used for the inspection.
U.S. Pat. No. 6,088,423-A discloses a method whereby three stationary radiation sources give forth x-rays in three planes parallel to one another, which run vertically to the travel direction. From the data of the three corresponding detector arrays, a computer determines possible contours of the articles in the object and calculates for each article an estimated effective atomic number Zeff and an estimated density. In this manner, the intensities of two energy ranges are evaluated, via the known dual-energy-method.